基于光纤光栅的编织复合材料多点热应变监测

为研究三维编织复合材料的热特性，本文利用编入编织复合材料结构的光纤Bragg光栅传感器来测量其内部多点热应变。为消除光栅自身温度受温度的影响，本文提出了用另一个自由状态光纤Bragg光栅对其进行温度补偿的方法。通过实验获得了编织复合材料的热应变与温度关系曲线。实验结果表明，碳纤维／环氧树脂三维编织复合材料结构的编织角较小时，在编织方向上的热膨胀率为负。

Distributing Measurement of Multipoint Internal Thermal Strain of 3D Braided Composite Using Fiber Bragg Grating Sensor

Due to the three-dimensional performance of 3-D braide d composites, coupled with the shortcomings of currently-adopted experimental m ethods, it is difficult to measure the internal parameters of materials, hence c auses it difficult to understand the material performance. To study the thermal performance of the 3-D braided composite, a method for measuring its internal m ulti-point thermal strain with co-braided in fiber Bragg grating sensor is res earched. To eliminate the temperature influence caused by the temperature change to the thermo-optic coefficient of the fiber Bragg grating, a method is used t o compensate the influence using another fiber Bragg grating at liberty. The rel ationship of the thermal strain of the braided composite and the temperature is obtained by experiments. Experimental results show that in the braided direction , the thermal expansion coefficient of carbon fiber/epoxy 3-D braided composit e is negative when the braided angle is comparatively small.